0:01

The next thing that we look for is background parenchymal enhancement.

0:04

And that can be described as minimal, mild, moderate, or marked.

0:09

And again, that's kind of a spectrum. A little bit subjective.

0:12

And then the background can be described as either symmetric or asymmetric.

0:18

And we assess this on the first post contrast subtraction series.

0:23

This is an example of a patient with minimal background parenchymal enhancement.

0:27

So you can see, since this is a subtracted image,

0:30

only the enhancing parts are going to be really well visualized.

0:36

So you can see blood vessels,

0:39

those are going to be bright, but there's really not very much happening

0:42

here in the breast tissue, as far as enhancement.

0:46

And then, this would be an example of mild background parenchymal enhancement.

0:50

There's a little bit more high signal intensity within that breast tissue.

0:57

Next would be moderate background parenchymal enhancement.

1:00

Here's a patient with a busier breast tissue.

1:03

There's some...

1:05

She has some cysts and some areas of non-mass enhancement,

1:09

but this background is more moderate So, basically, more enhancement.

1:16

And then here's an example of a patient with marked background parenchymal enhancement.

1:21

This happens to be a patient who's

1:22

currently breastfeeding and that can certainly increase that background

1:27

parenchymal enhancement.

1:29

We often will see marked background parenchymal enhancement,

1:33

abbreviated as BPE, in a patient who is breastfeeding.

1:38

So marked BPE.

1:41

And this is an example of asymmetric BPE.

1:45

All of the other examples we looked at

1:46

were fairly symmetric from side to side, but this patient is asymmetric.

1:52

And in this case,

1:55

the right side has marked background parenchymal enhancement and the left side, really,

1:59

doesn't have much enhancement at all.

2:01

And the reason for this was that the patient have had a lumpectomy

2:06

on the left side in the past, and have had a whole breast radiation to the left breast,

2:11

which is one of the things that can reduce background parenchymal enhancement.

2:17

So, it's important to think about factors

2:20

that are affecting background parenchymal enhancement, and that can include the phase

2:25

of the menstrual cycle, adding hormones, like hormone replacement

2:30

therapy, some form of oral or patch type

2:35

contraceptives, an IUD that emits hormones, and some supplements.

2:43

Some of our patients are on hormonal

2:45

suppression, either for breast cancer treatment or chemo prevention.

2:50

And when that stops, they can have a rebound where their

2:53

background parenchymal enhancement increases after stopping therapy.

2:58

And then breastfeeding,

2:59

which makes the breast very proliferative, can increase BPE as well.

3:05

Anti-hormonal therapies such as Tamoxifen and Aromatase Inhibitors

3:11

can decrease background parenchymal enhancement, often quite significantly.

3:15

And then, as a patient naturally goes through menopause, that will decrease BPE.

3:21

And like we mentioned before,

3:22

radiation therapy, which is often unilateral, will decrease BPE.

3:28

So moving on to a case. This is a 33-year-old woman who's

3:32

currently breastfeeding and has a recent diagnosis of left breast cancer.

3:38

Okay, so in this case, I'm showing the T1-weighted non fat-saturated image

3:46

on the left side and the subtracted image on the right side.

3:52

And just wanted to show you that you can have extreme fibroglandular tissue and

4:00

marked background parenchymal enhancement, which this patient does have.

4:06

Just going through

4:09

this case, you can kind of see that, that she enhances quite a bit.

4:13

And this was a breastfeeding patient.

4:18

And in other cases,

4:21

there can be a mismatch where the amount of fibroglandular tissue does not

4:27

really match the amount of background parenchymal enhancement.

4:32

And we'll look at that next.

4:34

So our next case is a 57-year-old woman for high risk screening breast MRI.

4:39

In this patient, we can see that there is, again, extreme fibroglandular tissue,

4:45

and the background parenchymal enhancement is actually pretty mild.

4:49

And as we scroll through this, we can see that

4:55

other than blood vessels and a little bit of background, there's not very much.

5:04

So we can really see here that you can

5:07

have a lot of fibroglandular tissue that really doesn't enhance with MRI.

5:12

So this can help us in patients who have

5:15

a lot of breast tissue density on their mammogram.

5:19

They may have a difficult ultrasound as well, but screening them with breast MRI

5:25

may be very helpful because their background is pretty quiet,

5:30

and if something new appears, we should be able to see it with MRI.